AT1780
Preliminary Product Information
640kHz/1.2MHz,Low-Noise Step-Up
Current-Mode PWM Controller
Features
• 1.6A,0.21Ω,14V Power MOSFET
• Operating input voltage:+2.6V to +5.5V
• Adjustable Output from V
IN
to 12V
• 640kHz /1.2MHz pin selectable switching
Frequency
• 0.1μA shutdown Current
• Built-in Soft-Start function
• Small 8-Pin MSOP
Package
General Description
The AT1780 is a current-mode step-up DC/DC
converter with a 1.6A, 0.21Ω power MOSFET.
The soft-start function is programmed with an
external capacitor, which sets the input current
ramp rate. It is ideal for generating bias voltages
for LCD panels. Pin selectable frequency 640KHz
or 1.2MHz operation results in a low noise output
that is easy to filter and faster loop performance.
An external compensation pin provides the user
flexibility in determining loop dynamics, allowing
the use of small, low equivalent series resistance
(ESR) ceramic output capacitors.
*Protected by U.S. Patent # 6,791,368
Applications
• LCD Displays
• Digital Cameras
• Portable Applications
• Hand-Held Devices
Block Diagram
VIN
COMP
SHDN
Power
ON/OFF
Reference
1.24V
SOFT-
START
4uA
SS
BIAS
-
+
Enable
Error
Amplifier
FB
1.24V
-
gm
+
+
Clock
Comparator
-
R
Q
N
LX
S
GND
FSLC
Oscillator
Ramp
Generator
+
+
CURRENT
SENSE
Aimtron reserves the right without notice to change this circuitry and specifications.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878 Fax: 886-3-563-0879
WWW:
http://www.aimtron.com.tw
3/24/06 REV 1.1
Email:
service@aimtron.com.tw
1
AIMTRON [ AIMTRON TECHNOLOGY ]
